To see the oe tray icon click on the arrow button next to clock on taskbar to expand tray icons:

What can i do with Tray icon?
If you click (left click) on tray icon, Outlook express window will hide, it will hide from taskbar also. This gives you the ability to have Outlook Express open but not showing window or on taskbar, To show it back again click again on Tray Icon.

Tray icon menu:
To bring tray icon menu, Right click on tray icon and a pop-up menu will appear.

Once it is checked (Enabled), every time you minimize the Outlook express window it will not appear on taskbar (to bring it back you muct click on Tray icon (left click). This can help to free space on your taskbar.
To disable back this feature, click on "Auto Hide to tray" again so it will be unchecked (disabled) again.

"Work Offline" menu: If you click on that menu you will notice that it will be checked and oe will restart and work in "Offline Mode" (Will not be able to send or receive emails). You can uncheck it to get OE back Online.

"Hide OE Windows when minimized" does the same job like "Auto hide to tray" menu described above.

"Create OE shortcut to run without Administrative rights" Will create a new shortcut on desktop for Outlook express. That shortcut can be used to Import .EML files on Outlook Express that is not possible when running OE normally.

"Block images and other content in HTML e-mail" setting that is missing from Outlook Express settings can be enabeld or disabled here on tray icon settings.

On the left you will notice the Buttons that can be used for browsing your Email Folder (DBX files) and Address Book file (WAB file) or changing their path.

Another (related) question : Is it possible to drag and drop folders full of .eml files and have the path recreated (if it doesn't exist) in Outlook Express

Also, I see in the (source) folders thar there are other files other than .eml files. I presume that it would not be possible to drag and drop those files into OE folders. When I try it OE very kindly starts an email which I presume could be used to send it to my "new" self.

Another option may be to change the path for OE so that it points to the old "identities\{khjgjghk}\m$\outlookexpress". Is that correct?

You must first create folders on oe to drom eml file in them. Changing the path of your dbx files to dbx files you have backed-up is correct, that way you can have old emails without need to import them